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[Ultrastructural Patterns of Interactions between Murine Lung Macrophages and Yeast Cells of Cryptococcus neoformans

Amaliya Stepanova1, Natalia Vasilyeva1, Masashi Yamaguchi2

  • 1North-Western State Medical University named after I.I. Mechnikov: Kashkin Research Institute of Medical Mycology of St. Petersburg.

Medical Mycology Journal
|March 2, 2018
PubMed

Insights

Murine lung macrophages interact with Cryptococcus neoformans yeast cells, leading to yeast lysis, macrophage death, or latent infection. This study reveals a new mechanism for polysaccharide capsule elimination by macrophages.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Cryptococcus neoformans is a fungal pathogen causing cryptococcosis.
  • Host immune responses, particularly macrophage interactions, are crucial for controlling C. neoformans infection.
  • The role of fungal cell viability and developmental stage in macrophage interactions remains incompletely understood.

Purpose of the Study:

  • To investigate the ultrastructural patterns of interaction between murine lung macrophages and different virulence strains of Cryptococcus neoformans.
  • To elucidate the mechanisms by which macrophages eliminate C. neoformans, focusing on capsular polysaccharide removal.
  • To determine the influence of C. neoformans developmental stage on host-pathogen interactions.

Main Methods:

  • Transmission electron microscopy was used to examine the ultrastructure of macrophage-C. neoformans interactions.
  • Murine lung macrophages were co-cultured with low- and high-virulence strains of C. neoformans.
  • Interactions were analyzed at the seventh post-experimental day.

Main Results:

  • Macrophages exhibited four distinct interaction patterns with C. neoformans: complete capsule loss and yeast lysis, partial capsule loss and macrophage destruction, latent intracellular localization, and ingestion of senescent/dead yeast with capsule loss.
  • The outcome of macrophage-C. neoformans interaction depended on the viability and developmental stage of the yeast cells.
  • A novel mechanism for the elimination of C. neoformans capsular polysaccharide by murine macrophages was identified.

Conclusions:

  • Macrophage-mediated clearance of C. neoformans is a complex process influenced by fungal viability and developmental stage.
  • The findings highlight a new pathway for capsular polysaccharide removal, impacting cell-mediated immunity against C. neoformans.
  • Understanding these interactions is critical for developing effective therapeutic strategies against cryptococcosis.
Keywords:
C. neoformansmacrophagesmurine lungstrainsultrastructurevirulence

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